from: America's Best Loved Community Cookbook Recipes, 1996
Makes about 3 dozen Whoopie Pies
1. Preheat oven 400º
2. To make cookies: In a medium mixing bowl, combine the 2 cups flour, the 1 cup sugar, the cocoa powder, baking soda, baking powder, and salt. Add the sour milk, water, and the ½ cup shortening. Beat with an electric mixer on low speed until combined.
3. Beat on medium speed for 2 minutes more. Add the whole egg and the egg yolk; beat for 2 minutes more.
4. Drop the dough by rounded teaspoonfuls 2 inches apart onto an ungreased baking sheet. Bake 6 minutes or until the top springs back when lightly touched in the center. Remove the cookies and transfer to wire cooling racks to cool.
5. Meanwhile, to make the filling: In a small mixing bowl, combine the ½ cup shortening, the 2 tablespoons flour, the 1 tablespoon granulated sugar and the vanilla. Beat with an electric mixer on medium speed for 30 seconds.
6. Slowly add just 1 ¼ cup of the powdered sugar. Beat well. Add the milk. Gradually add the remaining powdered sugar. Beat well.
7. Spoon about 2 tsp. of the filling onto half of the cooled cookies. Top with the remaining cookies and sandwich together.